This was the thesis I did when I studied for Industrial Engineering at De Nayer.
Do do this project/thesis we had some binoculars with a camera pointing towards what we are looking.
Another camera was looking to the eye's iris in order to register where the person was looking to.
With all the data I wrote a program in C that could interpret and register products where the person was looking to.
The screens will show you a bit what the result of the program was.
The paper can be found at: http://www.eavise.be/mastertheses/Ichiche.pdf